I'm not aware of any features in MSAS that would cause
this but Norton Internet Security has Pop-up window
blocking enabled by default which could cause links in
emails and sites not to open, If you have a different
Antivirus/Antispy also check them for a similar Ad-
Blocking feature.
If it's Norton Try Turning off Ad-Blocking from the main
menu or press configure and uncheck the box "PopUp Window
Blocking" and then press OK, If you think its related to
MS Antispyware, Right click the MSAS icon in the system
tray (Bullseye) and change "Security Agent Status" from
Enable to Disable then test the links again. Remember to
re-enable the protection after you have checked the
links. If you still cannot open links then shut down MSAS
using the system stray icon and see if the links work,
Use Start Menu > AllPrograms list to restart MS Antispy
after checking.
Andy